Pump construction



March 2, 1943.

R. R. CURTIS 2,312,525 PUMP CONSTRUCTION Filed Sept. 5, 1941 2Sheets-Sheet 1 March 2, 1 R. R CURTIS 2,312,52

PUMP CONSTRUCTION Filed Sept. 5, 1941 20 &-

2 Sheets-Sheet 2 Puss-E44 1Q. ("oer/s.

Pat'ented Mar. 2 1 943 2,312,525 rum CONSTRUCTION Russell R. Curtis,Dayton, Ohio, assignor to Curtis Pump Company, Dayton, Ohio, acorporation of Ohio Application September 5, 1941, Serial No. 409,644

15 Claims.

The present invention relates to a fuel system and more particularly toa booster pump con.- struction for an aircraft fuel system.

The pump portion the assembly of this invention is of the type isclosedin my copending application entitled Booster pump for aircraft fgilsystems," Serial No. 352,064, filed August 10, 1 0.

It is customary in all fuel systems of the force feed type to provide atleast one power .driven pump to assure the proper delivery of fuel to anengine. In aircraft fuel systems, a plurality of such pumps are usuallyprovided in the delivery line from the fuel tank to the engine. Thepumps are so sequentially arranged that the discharge of one pumpassures adequate delivery of fuel to the suction side of the next pump.

Furthermore, this arrangement of pumps must be such as to maintainadequate delivery of fuel under awide variety of operating conditionssuch as experienced in operating aircraft at various altitudes with theresultant changes in temperature and pressure. Under certain conditions,less than or all of the pumps may be required in operation.Consequently, each pump must'be so independently driven that itsoperation is controlled by the pilot. One fuel pump is therefore usuallydriven by the aircraft engine for delivering fuel to the engine underall normal conditions. Additional pumps are either hand driven orseparately power driven at the pilot's discretion. This assures properfuel delivery under abnormal flying conditions at very high altitudes orduring emergencies when one or more of the other pumps partially orcompletely fail to operate.

, Generally. the present invention provides a centrifugal booster orauxiliary pump of the type which separates gas from a gas-liquid fuelmix- ;ture and delivers fully liquid fuel under pressure tothe deliveryline of the fuel system. Motive power, separate from the aircraftengine, such as an electric motor, is provided for driving the boosterpump and its operation is controlled as desired usually by a switchbetween the pump and a source of electrical energy.

' A centrifugal pump is preferably used, as it provides a by-passthrough the impeller'when not in operation.

The assembly of such a pump and a driving member therefor, such as anelectric motor, requires the provision of sealing means therebetweenalong the drive shaft for' preventing leakventing propagation of flamefrom the motor portion to the pump portion.

It is also highly desirable to provide an air-circulating system forcooling the motor and for continuously scavenging the motor, the flamebarrier construction, the seal construction and the shaft bearingadjacent thereto.

It is therefore an object of the present inven tion to provide anauxiliary pump for a fuel system which is effectively sealed from itsprime mover.

Another object o fthe present invention is to provide a vapor-scavenged,air-cooled power driven auxiliary pump unit for a fuel system which issmall, compact, and easily interposed in the delivery line of thesystem.

A further object of the present invention is the provision of a drivenbooster pump unit for aircraft fuel systems which may be mounteddirectly on a fuel tank at any position below the hydraulic gradient ofthe fuel.

A still further object of the present invention is the provision of anelectric motor driven booster pump unit for aircraft fuel systems whichis eifectively sealed against fuel leakage from the pump portion to theelectric motor portion and is further sealed against flame or sparkpropagation from the electric motor to the pump portion.

Another and still further object of the present invention is theprovision of a slip stream actuated vapor scavenging and air-coolingsystem for the driving motor of an auxiliary or booster pump.

A still further object of the present invention is the provision of anelectrically driven auxiliary booster pump for aircraft fuel systemswhich is flame and explosion proof.

The novel features believed to be characteristic of the presentinvention are set forth with particularity in the appended claims. Theinvention itself, however, both as to its organization and manner ofconstruction, together with further objects and advantages thereof, maybest be understood by reference to the following descripage of liquidsfrom the pump portion to the motor portion and also a barrierconstruction or pretion taken in connection with the accompanyingdrawings, in which:

Figure 1 is a fragmentary view in vertical crosssection, with parts inelevation, of an airplane wing and wing mounted fuel tank illustratingthe manner in which the booster pump unit of this invention is connectedto the fuel tank and the manner in which a tube or pipe extends from theunit into the slip stream of the airplane for actuating the pump motorvapor-scavenging and air-cooling system;

Figure 2 is an enlarged longitudinal cross-sectional view, with parts inelevation, of the pump construction illustrated in Figure 1;

Figure 3 is a fragmentary and enlarged longi- 'tudinal cross-sectionalview of a portion of Figsubstantially along the line IV-IV of Figure 2.

As best shown in Figure 1, a pump assembly l0, including a prime movertherefor, is illustrated as being directly connected to a fuel tank Hand depending perpendicularly from the flat bottom wall thereof, alongthe axis line A-A. The unit I is supported within an aircraft win I 2 inspaced relation from the lower edge l3 thereof- Brackets l4 and I5support the tank ll above the lower wing edge I 3.

It is to be understood, of course, that although the pump assembly In ofthe present invention is illustrated as forming a portion of an aircraftfuel system, the device is adapted for use with any vehiclein whichliquid fuel is'delivered from a fuel tank. to a prime mover for thevehicle. It is to be further understood that the pump assembly may be,if desired, connected perpendicularly to a side wall of the tank alongan axis such as BB in Figure 1. While a perpendicular mounting of thepump on the tank wall along the axis A-Ais preferred, the pump willoperate satisfactorily in any angular position,

' between the axes A-A and BB. However, the

most eflicient mounting of the pump assembly III is in dependingvertical relation along the axis line A--A as shown in order-thatthe-pump be positioned as far as possible below the hydraulic gradientof the fuel tank and freely receive fuel from the tank.

or course, when the tank fills the space between the top and bottomsurfaces of the wing side mounting along the axis BB is used. Thisconnection introduces the undesirable feature of maintaining thehydraulic gradient above the pump throat, so that the tank can never bedrained as completely as when the pump depends from the bottom wallthereof.

The pump and prime mover assembly is best illustrated in Figure 2. Thepump construction is preferably of the centrifugal booster type such asdisclosed in my copending application entitled Booster pump 'foraircraft fuel system,"

Serial No. 352,064, filed August 10, 1940. This construction provides atapered throat member or ring l6 mounted .in the fuel tank outlet andmaintained therein by the pump' casing I! being connected to a wall ofthe fuel tank by means of studs or bolts l8 which pass through openingsl9 'in an outturned casing flange I la. The throat I8 is connected tothe casing, I! by means of screws 20.

The casing I! defines an internal volute chamber 2| communicating aroundthe inner periphery thereof with the throat inlet and opening on theouter periphery thereof into a discharge member 22 which in turn isconnected to a fuel delivery line F.

struction as seen when viewed in the plane taken 4 series of radiallycurved vanes 26 projecting from the flange toward the throat ring 16(Figures 2 and 3a). The impeller is secured to a driving shaft 2'l'by akey 28,a washer '29, and a nut 38 threaded on the shaft 21.

As best shown in Figures 3 and 3a, the key 28 is L-shaped and has oneleg 3| longer than the opposite leg 32. The shaft 21 is provided with alongitudinally extending partially circular keyway 33, such as used withWoodruff keys, in registry with a radially extending segmental circularkeyway 34 in the top face of the impeller flange 25. The key leg 3| iscurved to complementally seat within the keyway 34, while the key leg 32is curved to seat within a portion of the curved keyway 33. It is to benoted that when the key 28 is seated within th keyways 33 and 34, theleg 32 extends upwardly beyond the top surface of the impeller flange25. This extending 'portion of the key leg 32 is seated in the shaftkeyway 33 and extends into the aperture of the washer 29 and may or maynot extend above the washer. When the nut 30 is threaded to theexternally threaded portion of the shaft 21, the washer 29 surrounds theshaft and key leg 32 and seats against the key leg 3| to tightlymaintain the key within the keyways whereby the impeller is locked tothe shaft.

The circularly cut keyway 34 in the flange 25 is conveniently cut with amilling cutter and the leg 32 of the key, by being seated in the washer29, is held against radial displacement out of the thus cut slot. Thekey 28 is so shaped as to The pump has an impeller 23 mounted under thethroat ring I6 and spanning the throat inlet with its outer peripherycommunicating freely with the volute chamber 2|. The impeller 23comprises a hub 24, a flat disc flange 25, and a readily permit itsentry after the impeller has been assembled on the shaft. Thisiseifected by rocking the key into the aligned keyways to the positionshown and then tightening the nut against the washer as previouslydescribed. The heretofore required press fitting of a rectangularWoodruif key in a slot formed longitudi-- nally in' the shaft 21 beforemounting the impeller onthe shaft is thus avoided; i

The housing I! has a hollow intermediate restricted portion 36 defininga shaft well and which terminates in a flared portion 31 forming thehead of a prime mover housing 38. The shaft housing portion 36 isextended into the flared portion 31 to form a bearing housing 39.

An end cap 40 closes the other end of the motor housing 38. The head 31and end cap 40 are preferably bored at their ends to slidably flt ontothe ends of the housing 38 and the housing is clamped therebetweenbyinterlordraw bolt and exterior nut assemblies such as 38a and 3812respectively.

The prime mover is preferably an electric motor comprising an armature4|, spaced field coils 42 connected to the housing 38, a commutator 43,and a conductor 44 to the commutator brushes (not shown) by which theprime mover is energized from a source of electrical energy (not shown).

The pump shaft 21 extends through the electric motor and is supportedinthe end cap 40 by means of an anti-friction bearing 45. The shaft 27is also supported in the casing portion 33 by an anti-friction bearing48. A lug 46a on the bearing seats within a slot 46b in thecasing 39 tohold the outer race of the bearing against r0- tation.

The well 41, defined by the shaft housing portion 36, includes at oneend thereof a liquid seal construction 48 for sealing the pump and motorportions against liquid ,leakage therebetween.

In the details of construction best shown in 2,312,525 Figure 3, theseal construction 48 comprises a metal ring 49 loosely embracing theshaft 21 and seated on an inwardly extending shoulder 50 formed on theinner periphery of the casing portion 36 intermediate its ends. Themarginal edges at the periphery of the ring member 49 are of reducedthickness to define a slot be-' tween the body of the ring and the innerperiphery of the casing 36. A resilient ring member 52 is seated in theslot 5|. A ring Washer 53 is seated on the resilient ring member 52 andis urged thereagainst by a tubular seal nut 54.

Theseal nut 54 is externally threaded as at 55 for engaging internalthreads in the casing 36. When the seal nut 54 is threaded toward theshoulder 50, the washer 53 expands the resilient washer 52 in a radialdirection to tightly seal the slot 5|. This seal construction seals thewell portions on opposite sides of the shoulder 50 around the innerperiphery of the casing 36.

An angularly extending bore 58 is formed through the corner at the pumpend of the housing 36 for receiving therethrough a locking wire 51.Circumferentially. spaced apertures 58'are provided radially through thefree end of the seal nut 54. When the seal nut 54 has been threaded toits proper position, the aperture 58 nearest the bore 56 receivestherethrough the locking wire 51, the ends of which are twisted togetherto form a closed loop.

A compressed graphitic carbon seal ring. 59 slidably embraces theshaftfl for movement axially along the shaft. The carbon ring 59 and themetal seal ring49 are mounted in sliding face engagement. The carbonring 59 i covered with a resilient cushion washer or member 60preferably formed of fuel and oil resisting artificial rubber such asNeoprene. The cushion washer snugly engages the shaft?! in sealingrelation therewith. A cup member 6| has a reduced neck end slidablysurrounding the shaft 21 and an enlarged skirted end surrounding thecushion member 60. Axially extending tangs or fingels em and Bib on thereduced end of the cup member Gl' enga e within slots 24a and 24b in theimpeller hub 24 to form a positive drive connection with the impeller. Acoil spring 92 is interposed between thecup member El and the impellerflange 25, so that a constant force is exerted on the resilient cushion60 for maintaining the carbon ring 59'tightly against the metal sealring 49. At the same time the urging of the cup by the spring serves tosqueeze-the resilient Inasmuch as some liquid fuel or vapor may leakfrom the chamber in the well which is adjacent the impeller to thechamber adjacent the motor, even with the provision of an efficient sealconstruction such as 48, it is necessary to provide a drain for suchmaterial. As best shown in Figures 2 and 4, the casing I! hascircumferentially spaced web portions 65 extending between the pumpchamber defining portion and raised portions 66 on the enlarged casinghead 31.

These raised portions provide drain passageways 61 communicating withthe well 41 below the shoulder 50 and they slope outwardly to theperiphery of the head 31. The passageways 6'! are internally threaded attheir outer ends for a purpose to be later described. a

A flaredfiinger member 68 has a tubular end 69 tightly embracing theshaft 21 adjacent the shoulder 50 and an outwardly flared skirt 10extending in a direction axially of the shaft I away from the sealconstruction 48. Any liquid leaking from the pump end of the devicethrough the seal 48 is peripherally urged by the flinger 1 member 68against the inner periphery in the ring in the skirted portion of thecup to insure rotation of the ring 60 with the cup, and the ring 60 inturn drives the carbon ring to effect sliding face engagement with themetal ring 49.

This construction provides a seal around the shaft dividing the well 41into two isolated chambers. r

These two chambers in the well are thereby effectively sealed againstexcessive liquidleakage therebetween.

It is preferred that graphitic in the rotating seal ring 59, as itprovides sat sfactory wear and seal characteristics during the pressedsliding engagement with'the face of the metal seal ring 49. It is to beunderstood, however, that any other suitable material having similarproperties may be used.

The frictional drive for the rotating carbon seal ring 59 through. theresilient ring 60 and cup 9| has been found desirable due to thefragility of the carbon ring which will chip or crack if driven directlyby the shaft.

carbon be used 15 adjacent the shaft.

15 has one end of its outer periphery sized for' well of the casing 36where it drains through one or more of the drain openings 61.

A flame barrier construction Hg, for preventing propagation of flamefrom the motor to the pump, is interposed in the well 47 between theilinger 68 and the anti-friction member 46.

This construction H includes a sleeve member 12 having one end 13 snuglyengaging a portion of the shaft for rotation therewith. The end 14 ofthe sleeve 12 is axially recessed as at A second sleeve member snuglyengaging the wall of the well 41. The opposite end of the sleeve 16slopes inwardly toward the longitudinal axis of the shaft 21 to providea frusto-conical surface 11 terminatin in a cylindrical portion 18 whichextends into the flared skirt portion 10 of the flinger member 18. Theinner peripheral surface of the sleeve 16 i so shaped as tocomplementally enclose the entire outer periphery of th sleeve 12. Aportion of the sleeve 16 extends into the recess 15 and includes thereina portion of the shaft 21 from the bottom of the recess to a pointadjacent the restricted end 69 of the flinger memher.

The inner periphery of the sleeve 16 is sized to embrace the sleeve 72and a portion of the shaft 21 in spaced relation therefrom to define atortuous conduit 19 therebetween.

The clearance space or conduit 19 serve the purpose of sealing flamepropagation from within the electric driving motor to the well 41. It iswell known that flame will not pass through tortuous openings of reducedsize, th walls of which are composed of materials which readily absorbheat, and since it is intended to deliver gasoline as the fuel by thepump, it is necessary that the pump and seal portions be made explo- Vsion-proof. Furthermore, as the pump assembly the flinger member 68 andwill drain over the sloping surface 11 into one of the outlets 81.

As the cylindrical portion 18 of the seal sleeve 18 extends upwardlyinto the fiinger member, there will be no liquid fuel leakage into theclearance space 19.

In order to further insur against possible explosion of gasoline vaporor liquid in the'motor in the event the above described 'sealconstruction does not eliminate all passage of liquid gasoline or thatgasoline vapor might be trapped in the flame barrier construction, anair circulating system is provided to sweep out all vaporsand liquidsbeyond the seal 48 through a drain passage 81. Any fuel that leaks intothe well 41,

even though drains 61 are provided, will evaporate and some vapor mighteventually find its way through the flame barrier defined by theclearance space 19. This vapor leakage would not onlyprovide anexplosion hazard but would dissolve the lubricant sealed in theanti-friction bearing 48 causing the bearing to eventually fail. Thishazard is eliminated by providing, a system for circulating air throughthe driving motor, the

clearance space 19, and the well 41 to continuously scavenge the motorand the flame barrier construction;

To effect air circulation, the end housing 40 for the electric motor hasa plug 80, with a porous core 8| preferably of compressed and sin-teredpowdered metal therein. The plug 81l-i threaded into a threaded opening82 in the end housing 48 providing an air intake into the end of themotor remote from the pump construction.

As shown in Figures land 4, with the pump assembly l mounted verticallyalong the axis A-A, a tube 83 is connected to one of the drain openings81 by means of a threaded connector member 84. When the pump assembly ismounted horizontally along the axis 13-3 or angularly between thevertical and horizontal axes, the tube 83 is connected to the lowermostdrain opening 81. The end 85 of the tube 83 extends into the stream ofair which flow past the vehicle. In an aircraft installation, the end 85is positioned in the slip stream to draw air out of the tube 83. Theother drain openings 8'! are plugged by plu members 85 so that suctionthrough the tube 83 exhausts all fluid and liquid from the well 41. Thisexhaust not only drains liquid fuel which has leaked through thesealmember 48 but also scavenges the vapor formed by the vaporized fuel andcauses a flow of air through the intake plug 80 and entirely through theelectric motor. This fiow of air is further beneficial in that iteffects a cooling of the motor. I'he'air flow then passes by theanti-friction bearing 48 through the slot 48b and the, clearance opening19 into the well 41 where it is exhausted through the selected drainopening 81.

The porous material 8| used in the air intake plug 88 should be of suchconstruction that its porosity permits fairly free flow of air into thecasing 40 but prevents flames from propagating outwardly if an explosiontakes place within the motor. While the intake plug 80 is preferablypositioned in the end housing 48 in order that flow of air will passentirely through the motor and a cooling effect will thereby beobtained, it

is to be understood that the intake may be positioned anywhere along thelength of the motor and even in one of the unused drain openings 81. Inthis manner, the well 41 is scavenged of all liquid and vapor fuelthereby eliminating any seepage into the flame barrier II.

It will beapparent from the foregoing that I have provided a driven pumpassembly in which the pump and motor portions thereof are effectivelysealed against undue leakage of liquid fuel or fuel vapors therebetween;which is scavenged of any liquid fuel or fuel vapors seeping between thepump and motor portions; which is explosionproof; and which provides anair-cooled drivi motor construction. l

While a particular embodime'nt only of this invention has beenillustrated, it will, of course. be understood that the invention shouldnot be limited thereto, sin-ce many modifications may be made, andtherefore it is contemplated by the appended claims to cover all suchmodifications as fall within the true spirit and scope of th presentinvention.

I claim as my invention:

1. In a fuel system for a vehicle including a fuel tank, a pump fordelivering fuel from said: tank to a delivery line, a motor for drivingsaid pump, and means for sealing'said pump and motor against liquidleakage therebetween, the improvement of means defining an"air flow paththrough said motor, and a drain device adapted to induce air flowthrough said path to sweep out any fuel which leaks past the seal means;

2. In a fuel system for a vehicle including a fuel tank, a pump fordelivering fuel from said tank to a delivery line, a driving motor, ashaft driven by said motor for drivingthe pump, and means for sealingsaid shaft against leakage between the pump and the motor, theimprovement of means defining an-air flow path through a shaft wellbetween the motor and pump, and a motor-driven pump shaft extendingthrough said well in spaced relation therefrom, the improvements ofspaced shaft seal and flame trap constructions in said well definingtherebetween a localized well chamber, means defining an air flow paththroughsaid motor, and means connecting the localized well chamber withthe air stream adjacent the vehicle to draw air through said air pathand said flame trap for scavenging the well chamber.

4. In a pump and electric motor assembly for a vehicle including ahousing defining a pump chamber, a motor chamber, and a shaft welltherebetween connecting said chambers, the immovements of spaced pumpseal and flame trap constructions in said well and defining therewith alocalized well chamber, a drain outlet for saidwell chamber, an airinlet for said well chamber,

and means for inducing air flow through the outlet to scavenge the wellchamber.

5. In an aircraft fuel system including a fuel pump, a shaft for drivingthe pump, and a housing surrounding the shaft, the improvements of.spaced, shaft seal and barrier constructions in said housing definingtherebetween a localized chamber in the housing, an air inlet to saidchamber, and means connecting said chamber with the slip stream of theaircraft to draw air therefrom for scavenging the chamber.

6. In a fuel system fora vehicle having a fuel tank, a pump fordelivering. fuel from the tank to a delivery line,-a driving motor, apump shaft driven by said motor, a housing for said pump shaft andmotor, and sealing means spaced longitudinally along said shaft betweenthe shaft and housing defining a localized housing chamber therebetween,the improvements of a flinger on said shaft between said sealing means,means defining an air flow path through the motor and one of the sealingmeans into said chamber, said chamber having a plurality of outletsadjacent said flinger, and a suction line extending from one of saidoutlets into the stream of air flowing past the vehicle to exhaust fuelfrom the chamber and to draw air through the motor and said one sealingmeans.

7. In a pump and electric motor assembly in cluding a pump shaftdirectly driven by said motor, the improvements of a housing for saidassembly having a passageway between the motor and pump freely receivingsaid shaft therethrough, sealing means in said passageway comprisingrelatively rotating contacting sealing rings attached respectively tosaidshaft and to a wall of said passageway, relatively rotating spacedinterfitting members attached respectively to said shaft and to a wallof said passageway on the motor side of the sealing rings definingtherebetween a tortuous path sealing against flame propagation from themotor to the pump, a iiinger member on said shaft between said sealing.rings and said interfitting members, and a drain outlet communicatingwith the passageway adjacent the fiinger.

8. In a pump and motor assembly, a shaft driven by the 'motor fordriving the pump, a housing for said assembly having a reducedconnecting passageway between the pump and motor freely accommodatingsaid shaft, said passageway having an internal shoulder, a stationaryseal ring a seated snugly on said shoulder and disposed freely aroundsaid shaft, a seal ring rotatable with said shaft in slidable engagementwith said sta-' tionary seal ring, means urging said rotatable seal ringagainst said stationary seal ring, a

flinger member on said shaft positioned between the seal rings andmotor, a second stationary seal member seated in said passageway betweensaid flinger member and the motor, and a second rotatable seal member onsaid shaft within said second stationary seal member, said seal membershaving their adjacent surfaces in spaced relation defining a tortuousnarrow path from the motor to said pasageway, said housing having adrain therein communicating with said passageway, and means extendingfrom said drain to remove any fiuid thrown thereinto by said fiinger orpassing through said narrow path from the motor.

9. In a pump and motor assembly including a shaft driven by said motorfor rotating a pump impeller carried on the shaft, the improvements of ahousing surrounding said shaft and having a shoulder on the innerperiphery thereof, a seal ring loosely embracing said shaft and seatedon said shouder, said seal ring having a reduced peripheral margindefining a slot between the body of said seal ring and the innerperiphery of said housing, a resilient gasket seated in said slot, aseal nut threaded into said housing against said gasket for expandingthe latter in said slot and maintaining the seal ring on said shoulder,a. second seal ringon said shaft in slidable face engagement with saidfirst seal'ring, a resilient member frictionally engaging said secondseal impeller for co-rotation, and, coil spring means between said sealcup and the pump impeller for maintaining said seal rings in tightsliding face engagement whereby the ends of said housing are sealedagainst liquid leakage therebetween.

10. In a pump and motor assembly, a shaft driven by the motor fordriving the pump of said assembly, a housing surrounding said shaft, acombined air flow conduit and flame trap in said housing between thepump and motor comprising a sleeve member sealingly engaging said shaft,and a second sleeve member sealingly engaging the inner periphery ofsaid housing and embracing saidfirst' sleeve member in spaced relationtherefrom, said members being mounted for relative rotation, and thespace between said members defining a narrow tortuous path of greaterlength than the length of said sleeve members.

11. In a pump and motor assembly, a shaft driven by the motor fordriving the pump of said assembly,-a housing surrounding said shaft, acombined fluid conduit and flame trap in said housing between the pumpand motor comprising a sleeve having a portion sealingly engaging theperiphery of said shaft and an axial recessed portion spaced from saidshaft, and a second sleeve having a portion sealingly engaging the innerperiphery of said housing and a conical portion sloping toward the axisof said shaft, said sleeves being" mounted for relative rotation, theinner periphery of said second sleeve being shaped to embrace said firstsleeve and a portion of said shaft in spaced relation therefrom, thespace between said members defining a tortuous path of greater lengththan the length of said sleeve members.

12. In a pump and motor assembly, a pump shaft driven by the motor fordriving the pump of said assembly, a housing surrounding said shaft,acombined trap and gas conduit in said housing between the pump andmotor comprising a sleeve having a portion at one end tightlyerntapering away from said one end toward the axis of said shaft, theinner periphery of said second sleeve being complementally shaped toembrace the entire periphery of said first sleeve and a portion of saidshaft in spaced relation therefrom to define a tortuous path, a flaredfiinger member tightly embracing said shaft for -rotation thereby andhaving a portion overlapping the tapered end of said second sleeve, andan outlet in said housing adjacent the base of said tapered portion onsaid second sleeve, said outlet exhausting any liquid thrown by saidflinger between the tapered base of said second sleeve and said housingand any gas drawn through said space between the sleeves.

13. In a fuel system including a fluid pump, the improvements of a primemover for said pump, a seal construction for sealing said prime moveragainst fluid leakage from the pump, and a trap construction for scalingsaid prime mover against flame propagation to the pump.

14. In a pump and motor assembly including a pump shaft driven by saidmotor and a housing providing a passageway between the motor 'and pumpfreely receiving said shaft, the imsaid shaft and rotatable with theshaft, a second sleeve member in said passageway disposed around thefirst sleeve member and snugly engaging a wall of the housing, and saidsleeve members cooperating to define a narrow el'ongated tortuous pathsealing the pump and motor against flame propagation therebetween.

15. In a pump and motor assembly including a pump shaft driven by saidmotor and a housing providing a passageway between the motor pump ireelyreceiving said shaft, the improve- I ment of a flame trap between thepump and motor comprising relatively rotating spaced interfltting partsin said passageway carried by said shaft and housing respectivelydefining therebetween a narrow path sealing against flame propagationbetween the motor and pump.

RUSSELL R. CURTIS.

